In silver halide color photosensitive materials, phenol or naphthol type cyan couplers are commonly used for forming cyan color images. However, those couplers have undesirable absorption in the regions of green rays of light and blue rays of light, so that they have a severe problem that they are responsible for considerable drop in the reproducibilities of blue and green colors. Therefore, solving this problem has been strongly desired.
As a measure for solving such a problem, the 2,4-diphenylimidazole type cyan couplers disclosed in EP-A2-0249453 were proposed. Since the dyes formed from these cyan couplers are reduced in undesirable absorption present in the regions of green rays of light and blue rays of light, compared with the dyes formed from the above-cited cyan couplers of phenol and naphthol types, an improvement in color reproducibility is brought about by those couplers, to be sure, but the color reproducibility attained by those couplers is not wholly satisfactory. Such being the case, a further improvement is required of them. In addition, those couplers suffer from a serious problem that they exhibit low activity in the reaction with oxidized developing agents (namely, low coupling activity) and the dyes formed therefrom are considerably low in fastness to heat and light. Accordingly, those couplers cannot serve the purpose of practical use as they are.
Further, the pyrazoloazole type cyan couplers disclosed in U.S. Pat. No. 4,873,183, JP-A-64-552 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-64-553, JP-A-64-554, JP-A-64-555, JP-A-64-556 and JP-A-64-557 can form dyes which are reduced in undesirable absorption present in green and blue regions, compared with conventional dyes, but they are still unsatisfactory in view of color reproducibility. In addition, they have a problem such that their color formabilities are markedly low.
Furthermore, EP-A1-0456226 discloses pyrroloazole type cyan couplers as cyan couplers capable of forming dyes excellent in hue. These couplers undergo an improvement over the above-cited couplers in view of color reproducibility, but the improvement is not yet very satisfactory. In addition, they have a drawback of causing serious color stain in unexposed areas, and their color formability is not on a very satisfactory level.
On the other hand, ensuring a high keeping quality in images is another matter of great importance to silver halide color photosensitive materials. The dyes formed from generally used phenol or naphthol type cyan couplers have a problem such that the colors thereof become muddy as a change to yellow is caused therein due to fading upon long-range storage under a high temperature and high humidity condition.
Under these circumstances, it has been desired tin the art to ensure satisfactory color reproducibility and high keeping quality in cyan color images formed in silver halide color photosensitive materials.